<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>单列布局</title>
    <style type="text/css">
        html, body{
            height: 100%;
            margin: 0;
        }
        .header{
            width: 100%;
            height: 60px;
            line-height: 60px;
            text-align: center;
            background-color: #000;
        }
        .container{
            width: 1200px;
            margin: 0 auto;
        }
        .header .container{
            height: 60px;
            background-color: orange;
        }
        .wrap{
            width: 100%;
            height: 100%;
        }
        .wrap .container{
            height: 100%;
            background-color: red;
        }
        .footer{
            width: 100%;
            height: 100px;
        }
        .footer .container{
            height: 100%;
            background-color: green;
        }
    </style>
</head>
<body>
    <!-- 头部 -->
    <div class="header">
        <div class="container"></div>
    </div>

    <!-- 主题内容 -->
    <div class="wrap">
        <div class="container"></div>
    </div>

    <!-- 脚部 -->
    <div class="footer">
        <div class="container"></div>
    </div>
</body>
</html>